When traumatic lumbar fractures occur, they are usually associated to severe and violent physiopathological mechanisms. According to Denis [11], shear injuries can be divided into two types: posteroanterior and anteroposterior. Anteroposterior forces are induced by hyperextension forces, resulting in fractures of the posterior column and pedicles conditioning a free-floating neural arch. Due to the complexity of these injuries, it is risky to propose a sole mechanism for the various thoraco-lumbar fractures. It seems likely that the injury in our case resulted from a violent combination of flexion and anteroposterior mechanism with a split phenomenon of the posterior arch away from their vertebral bodies and fracture of a spinous process of the adjacent level. In this case, and as it was previously emphasized by other authors, it is suitable to consider that lumbar muscles, intrinsic ligament characteristics and disc preservation played an important role in preventing subsequent vertebral displacement [9, 12]. Previous occasional cases with incomplete or intact neurologic function could be explained by spontaneous decompressive mechanisms associated with multiple pedicle fractures allowing the posterior elements to float in continuity [13, 14, 15].

Reviewing the proposed classification by Kaufer and Hayes in 1966 [9] and re-adopted by Ver et al. in 2019 [12], our patient´s injury can be situated as a Type 5 fracture of the lumbar neural arch, in which the line of disruption consists of bilateral fracture through either the pedicles or the pars interarticularis. The integrity of muscle and spinal ligament complex is crucial during thoraco-lumbar injuries, and their condition should always be determined by means of C-T scan and MRI. Even though there was no imminent displacement, the development of a double fracture with these characteristics made us doubt that implementation of simple conservative treatment with just an external immobilization may not be the best option. During surgery, this situation could be confirmed because an excessive displacement of the vertebral body was noticed while progressive pedicle drilling was performed.

Conservative treatment based on pain medication, external orthosis and sometimes epidural or trigger points injections is initially recommended for spontaneous bilateral pedicle and selective acute traumatic cases. The length of this management is not standardized and depends on clinical manifestations and radiological surveillance. According to Kögl [4], in cases of nondisplaced pedicle fractures and in the absence of neurological deficits, conservative treatment has been advocated because pedicle fractures tend to heal spontaneously with external bracing. However, this practice is associated with long-term immobilization and the risk of pseudarthrosis should be considered. Under these circumstances, the potential development of late instability or spondylolisthesis would lead to progressive disc degeneration [4, 10]. Surgery for these lesions must be proposed when an inadequate solution to the fracture is evident either by the development of spondylolisthesis, pseudoarthrosis, progressive secondary disc degeneration or if pain control mechanisms fail.

In cases where bilateral pedicle fractures at L2 and L3 are present, they may present a unique problem in terms of operative planning. The relative rarity of these injuries has led to a paucity of literature regarding surgical recommendations. Most authors tend to treat this type of trauma by surgery, which can be performed by anterior, posterior or combining both approaches depending on neurological status, stability and patient´s systemic condition [15]. It is essential to restore normal lumbar alignment, decompress neural structures and stabilize the lumbar spine. For this purpose, open reduction and rigid fixation are usually recommended [15]. Interbody fusion with its different variants complemented by posterior stabilization can actually be the optimal choice in cases where spondylolisthesis is present [17].

On the contrary, in exceptional cases when alignment is maintained associated with appropriate structural conditions, treatment options that are confined to preserve mobility of the affected segment are the best choice. Han et al [18] proposed a motion-preserving surgical option for nontraumatic, nondisplaced bilateral pedicle fractures at a single lumbar level. They inserted bilateral pedicle screws at L5 to reduce the fractured fragments, and by resecting the lower aspect of L5 spinous process, a rod is placed across the lamina connecting it to the screws. With this the need to fuse the adjacent levels was avoided. Recently Kogl et al [4], described technically an option to reduce and stabilize a bilateral L5 pedicle fracture. Combining the use of a navigation system and intraoperative fluoroscopy to confirm reduction of the fracture and detect fragment dislocation, they performed a percutaneous minimally invasive CT-guided off-label pedicle instrumentation without interbody fusion and inserted a couple of 7.3 mm traction screws to bring the fracture edges closer together with satisfactory fusion results.

Motion preservation procedures may be proposed in cases where an adequate reduction of the pedicle fractures is obtained, when the disc characteristics are maintained and in the presence of acceptable muscle-ligament complex condition. All of these circumstances were present in our case, so the decision to use pedicle screws and rods without intervertebral fusion will allow an appropriate restoration of the pedicles and subsequent stabilization of the double fracture. After optimal conditions of the segment are considered, withdrawal of the system will promote the motion properties in both segments. Contrary to Kogl´s procedure [4], although it is a very good surgical option, we considered that it would have been very risky to try this on our patient without taking the rest of the associated radiological findings into account.

It is important to emphasize that aggressive management with early surgical intervention allows prompt mobilization and more rapid rehabilitation. The high-energy nature of these injuries also warrants a thorough evaluation for other bony or soft-tissue injuries. With proper stabilization of the spine, many patients regain a reasonable degree of their neurological function and muscle strength. Chronic issues, such as pain, are susceptible to be managed adequately in a conservative manner [19].